Chuck (chuk), noun. 1. any device for holding a tool or piece of work, as in a lathe, drill or other machine.
Source: The World Book Dictionary, copyright by Doubleday & Company, Inc.

In our business, we use the term for any device attached to the spinner shaft, with the purpose of securing the substrate to the shaft while spinning.

Headway has designed thousands of different chucks, using various principles for holding, and made from a wide variety of materials as required by a customer's substrate(s) and process(es). Among the principles we have used for holding:

Headway is currently selling spinners that have three shaft-to-chuck interfaces. The lighter duty interface is for the PS Motor, for lighter substrates, to 10,000 rpm. These chucks are referred to as the EP Chucks.

The heavy duty chuck interface is used for the BD Motors used for heavier substrates, to 5,000 rpm. These chucks are referred to as the LS Chucks. Headway also sells an LS to EP Adapter for those customers that have a supply of EP type chucks they would like to use on their LS type of machines.

The PS80 Spin Cleaner has a unique chuck design, similar to the EP, but having an extra protective skirt. These chucks are referred to as the SC Chucks. Although similar in interface to the EP chucks, the two types are not interchangeable.

Headway still supports early non-current product with the AHT and AC line of chucks. The EP type chucks fit all prior EC100, EC101, PM101 type spinners.

Inertia (in·er·tia), noun. 1 a : a property of matter by which it remains at rest or in uniform motion in the same straight line unless acted upon by some external force b : an analogous property of other physical quantities (as electricity)

Moment of inertia:
a measure of the resistance of a body to angular acceleration about a given axis that is equal to the sum of the products of each element of mass in the body and the square of the element's distance from the axis
Source: Ask.com, WWWebster Dictionary

When spinning substrates, inertia is an extremely important factor. The inertia is a function of the square of the distance from the center of rotation to the center of mass. This means the power required to accelerate increases rapidly as substrates increase in size. The moment of inertia includes both the substrate and the chuck required to hold that substrate. A fragile substrate may require a chuck with tremendously more moment of inertia than the substrate alone.

Substrate (sub'strate), noun. 1. a substratum
Substratum (sub stra'tum), noun. 1. a layer lying under another 3. basis; foundation.
Source: The World Book Dictionary, copyright by Doubleday Company, Inc.

In our business, we use the term as a very generic reference to an object being processed, in that it is usually a supporting "layer" for work being accomplished whether that object be a silicon wafer, optical lens, microscope slide, compact disc master, flat panel display, sensor film, memory disc, etc.

Something must hold a substrate to the end of the spinner shaft. The wide variety of substrates require a wide variety of holding devices. We generically refer to the holding device as a chuck.